Alliances are made of groups of StargateWars players that bond together to work in each other's mutual interests. Examples of major Alliances are Omega, Dirty Dozen, Tauri Alliance, and the EPA. There are also many minor Alliances made up of real world friends and players hoping to become the next "big thing".
Alliances, in addition, often sign treaties to create a coalition. An example of this is the Coalition of Paragons, aka "CoP", which is formed by several major alliances such Omega, Dirty Dozen, their sister alliances, and several others. A coalition is not to be confused with sister alliances (e.g. Alpha of Omega and D12 of DD). The sheer strength and teamwork of both the average members and in particular the exceptional ones has led to the CoP being seen as an over-powered group of bullies.
There is also the EPA Confederacy which is comprised of a series of alliances with large member counts. The typical player strength of a Confederate being below average with a few exceptions has led many to dislike the EPAc and their NAPs with it as it puts many many bountiful farms on a "do not touch list"